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The Mike O'Callaghan – Pat Tillman Memorial Bridge, the key component to the Hoover Dam Bypass project, was the first concrete-steel composite arch bridge built in the United States, and it incorporates the longest concrete arch bridge in the Western Hemisphere. Opened on October 19, 2010, this four-lane highway bridge provides a crossing of the Colorado River for U.S. Route 93, linking Nevada with Arizona about 1,600 feet (about 500 meters) downstream from the Hoover Dam. This bridge is located about 30 miles (48 kilometers) southeast of Las Vegas, Nevada. At 840 feet (260 meters) above the Colorado River, this bridge is the second-highest one in the United States, following the Royal Gorge Bridge. Built as part of the Hoover Dam Bypass Project, which was successfully completed within budget at a cost of $240 million, the bridge portion cost $114 million (2010 prices).
Justification for a new bridgeThe bypass was constructed to improve safety, security, and traffic capacity. Through extensive studies, this bridge route was determined to be the best route for the bypass.
U.S. Highway 93, in conjunction with U.S. Highway 60 via Wickenburg, Arizona, is the primary highway between Phoenix, AZ and Las Vegas, two cities that have seen great increases in population since the completion of the Hoover Dam. The section of U.S. 93 that approached and crossed Hoover Dam was not adequate for modern traffic needs. It was too narrow, with just one lane in each direction, it had many dangerous curves, including several hairpin turns, and it had poor lines-of-sight, especially at night.
Through highway traffic combined with sightseeing and pedestrian traffic at the dam, the traffic often came to a standstill. As a consequence of the heightened security measures following the September 11, 2001 attacks, truck traffic over the Hoover Dam was diverted south to a bridge crossing the river at Laughlin, Nevada, in an effort to safeguard the dam from hazardous spills or explosions. This disruption, however, did not eliminate the threat of a possible attack on the dam, since regular traffic still passed over it. Hence, the new bypass and the bridge were intended to improve travel times, replace the dangerous roadway, and reduce the possibility of an attack or an accident at the site of the dam.
More than 17,000 cars and trucks are using the new bridge daily, a number expected to grow by 50 percent over the next 20 years. This bridge is a key component of the proposed Interstate 11 project.
Design
Planning and environmental work was completed and the environmental impact statement issued in July 1988. The design of the preferred alternative started in July 2001. Project design was by the Hoover Support team, led by HDR, Inc. and including T.Y. Lin International, Sverdrup Civil, Inc., and other specialist contributors.
The bridge has a length of 1,900 feet (579 m) and a 1,060 ft (320 m) span. The roadway is 900 ft (270 m) above the Colorado River and four lanes wide. This is the first concrete-and-steel composite arch bridge built in the United States. It includes the longest concrete arch in the Western Hemisphere and is also the second highest bridge in the nation, with the arch 840 ft (260 m) above the river. The twin arch ribs are connected by steel struts.
The composite design, using concrete for the arch and columns with steel construction for the roadway deck, was selected for schedule and cost control while being aesthetically compatible with the Hoover Dam. Sean Holstege in The Arizona Republic has called the bridge "an American triumph". USA Today called it "America's Newest Wonder" on October 18, 2010.
Pedestrian access is provided over the bridge to tourists who wish to take in a different view of the nearby dam and river below, but the dam is not visible for those driving across it. A parking area is provided near the bridge on the Nevada side at what was a staging area during construction. A set of stairs and disabled access ramps lead to the sidewalk across the bridge.
The naming of the bridge
In late 2004, the proposed bridge name honoring Mike O'Callaghan and Pat Tillman was announced at a ceremony by the Governor of Nevada, Kenny Guinn, and the Governor of Arizona, Janet Napolitano. O’Callaghan, a decorated Korean War veteran, was the Governor of Nevada from 1971 through 1979, and he was the executive editor at the Las Vegas Sun newspaper for many years until his death on March 5, 2004. Tillman had been a football player for the Arizona State University team and for the Arizona Cardinals team. He gave up his multimillion dollar career in the National Football League to enlist as an infantryman in the U.S. Army, but he was killed by friendly fire in Afghanistan on April 22, 2004.
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